1. Field of the Invention
The present invention relates to a variable valve mechanism of an internal combustion engine, which controls valve timing and valve lift of the engine in accordance with an operating condition of the engine.
2. Description of Related Art
Nowadays, variable valve mechanisms are commonly employed in automotive internal combustion engines for the superiority possessed by the mechanism. In fact, with the mechanism, fuel consumption and driveability under low speed and low load operation of the engine are both improved and at the same time, due to increased mixture charging efficiency, a sufficient output under high speed and high load operation of the engine is obtained.
According to a first aspect of the present invention, there is provided a variable valve mechanism of an internal combustion engine, which comprises a drive shaft driven by the engine; a control shaft extending in parallel with the drive shaft, the control shaft being rotatable about its axis to a given angular position in accordance with an operation condition of the engine; a swing cam rotatably disposed about the drive shaft, the swing cam actuating engine valves; a first eccentric cam tightly disposed on the drive shaft; a first link rotatably disposed on the first eccentric cam; a second eccentric cam tightly disposed on the control shaft; a rocker arm rotatably disposed on the second eccentric cam; a second link extending between the rocker arm and the swing cam; a first connecting pin through which a first arm portion of the rocker arm and the first link are pivotally connected; a second connecting pin through which a second arm portion of the rocker arm and an end of the second link are pivotally connected; and a third connecting pin through which the other end of the second link and the swing cam are pivotally connected, wherein the first connecting pin is fixed to either one of the first arm portion of the rocker arm and the first link.
According to a second aspect of the present invention, there is provided a variable valve mechanism of an internal combustion engine, which comprises a drive shaft driven by the engine; a control shaft extending in parallel with the drive shaft, the control shaft being rotatable about its axis to a given angular position in accordance with an operation condition of the engine; a swing cam rotatably disposed about the drive shaft, the swing cam actuating engine valves; a first eccentric circular cam tightly and eccentrically disposed on the drive shaft; a first link rotatably disposed on the first eccentric circular cam; a second eccentric circular cam tightly and eccentrically disposed on the control shaft; a rocker arm rotatably disposed on the second eccentric circular cam; a second link extending between the rocker arm and the swing cam; a first connecting pin through which a first arm portion of the rocker arm and the first link are pivotally connected; means for pivotally connecting a second arm portion of the rocker arm with an end of the second link; and means for pivotally connecting the other end of the second link with the swing cam, wherein the first connecting pin is fixed to either one of the first arm portion of the rocker arm and the first link.
The other objects and advantages of the present invention will become understood from the following description with reference to the accompanying drawings.